Article

This article presents the current state of the vascular flora and phytogeographic relations in the catchment basin of the river Roussenski Lom (lower and middle course). The paper includes: List of flora in the catchment basin of the river Roussenski Lom; Distribution of flora by systematic indication, biological type, origin and eco-geographical relations; Analysis of the distribution of the rare and endemic plants. A historical survey of the floristic investigations in the region is made. In the beginning of the 21st century for the flora in the catchment basin of the river Roussenski Lom are found 877 species distributed in 87 families and 399 genera in the period 1998-2004. The floristic and phytogeographic analysis does not include about 130 species reported in relevant literature only. The species found in this area represent 23, 1 % of the flora of Bulgaria.